1. Field of the Invention
This invention relates in general to electrical transformer enclosures and more specifically to a transformer tank with detachable cabinet interface.
2. Description of the Prior Art
Single phase padmounted transformers are installed in residential areas, and it is desirable that they be aesthetically designed and have no sharp comers or edges as well as having tamper-resistant interfaces between the cable component cover and the transformer tank. An example of such padmounted transformer enclosures is disclosed in U.S. Pat. No. 4,533,786. In that patent there is disclosed a metal "clam shell" type cover with a large steel cover hinged at the top and a sill approximately 6" high to which the cover is bolted. A variety of baffling was built into the cover and/or sill to meet the ANSI C.57.12-28 tamper resistance requirements. One of the problems with metal transformer covers or enclosures is that they are subject to significant corrosion problems. Such problems are encountered in coastal environment and even in non-coastal regions corrosion problems can be experienced due to fertilizers, road salt, irrigation systems, lawn equipment, etc. While stainless steel cabinets will solve the corrosion problem, such cabinets are expensive.
In U.S. Pat. No. 5,739,464 there is disclosed a cable compartment enclosure that is non-metallic, non-conductive and thus not subject to corrosion problems. In that patent the enclosure is of one-piece construction and does not require a cover hinge at the top and a sill. In that patent the composite hood design utilizes a simple, metal "knife-edge" interface on the transformer tank (male portion) and a grooved interface on the composite hood (female portion). While the composite hood design provided corrosion resistance for the hood, one deficiency of the design was the metal "knife-edge" of the tank that is susceptible to damage, either by handling (bent edges) or by installing and removing the hood (rubs paint off which starts corrosion). It would be desirable to provide a design to eliminate the metal "knife-edge" problem and add a small "adaptor" to the knife-edge of the tank to create a "knife-edge" of dent-resistance, corrosion-resistant material. It also would be desirable to be able to upgrade existing transformers to include a non-conductive enclosure.